There has been hitherto known an optical scanning-type image forming apparatus which scans illumination light from the tip part of an optical fiber toward an object and detects detection light reflected and scattered by the object or fluorescence generated in the object (see, for example, Patent Literature 1). In such apparatus, the optical fiber is held in part with the tip part for emitting the illumination light being oscillatable, and an actuator is disposed in the vicinity of the supporting part, so as to vibrate the optical fiber, to thereby scan the illumination light on the object.